This invention relates to a device for tensioning a retractable roof of a motor vehicle, and more particularly to such a device designed for a roof including a front element and a rear element that are mounted to be movable between a closed position in which said elements cover the passenger compartment of the vehicle and an open position in which said elements are folded away into the rear trunk of the vehicle, the elements being caused to move by two hinged arms, each of which is hinged firstly to the structure of the vehicle in the vicinity of the front edge of the trunk, and secondly to the front element of the roof, so that the two arms and their respective hinges form a deformable parallelogram, said device including abutment means carried by a first arm to come into abutment against the second arm when the two roof elements are in a relative position that is close to their closed position.
Such a device is known from Document FR-A-2 802 478.
During roof closure, the abutment means cause tension between the two arms, thereby stiffening the roof and therefore reducing the vibration of the roof while the vehicle is moving. In addition, the stiffening of the roof enables said roof to participate in the rigidity of the entire body of the vehicle, as the roof does in a vehicle having a non-retractable roof.
In the above-mentioned document, the abutment means are constituted by an eccentric which is adjusted by turning about a point that is fixed relative to the arm on which it is mounted, and the eccentric is locked when it comes into contact with the other arm when the elements are in a relative position that is close to the closure position.
Such an arrangement is generally satisfactory.
However, it has the disadvantage of being difficult to adjust. Unless it is adjusted almost perfectly, a certain amount of vibration can remain.
In addition, it is not always suitable, depending on the vehicle which it is to be used in. In particular, it can be difficult to implement when the distance between the arms at the desired abutment point is large.